THE DESIGN AND CONSTRUCTION OF MINI RADIO BROADCAST TRANSMITTER AND AUDIO CONSOLE USING FREQUENCY MODULATION (FM) WITH POWER RATING OF 1 WATT.

THE DESIGN AND CONSTRUCTION OF MINI RADIO BROADCAST TRANSMITTER AND AUDIO CONSOLE USING FREQUENCY MODULATION (FM) WITH POWER RATING OF 1 WATT

ABSTRACT

The early transmitter for radio broadcasting is so big and bulky that they do occupy numerous spaces. The circuitries are mainly designed with valves, which are big in sizes.

With the advent of semiconductor materials such as transistors electronic equipment are now becoming miniaturized such that small transmitters are now becoming handy and compact.

In line with this we choose to design a complete radio broadcasting equipment tat is compact and existence of semiconductor materials.

The system units are of two categories namely: audio console for the processing and mixing of musicals is basically a condenser microphone.

The transmitter unit is where the center frequency is provided. All these were designed to be in compact and small manner. This project is aimed at serving a community using a small and compact radio broadcasting equipment with a power watt of 1 watt a community of 1 kilometer in radius should be covered comfortable and the audio production very clear unlike the common noisy FM microphone project.

INTRODUCTION

This our project work is all about design and construction of a complete radio broadcasting equipment that is compact and miniaturized. It is capable of delivering a power output of 1 watt and assumed to cover a distance of 400 meters ie 200 meters radius depending on obstructions.

The transmitted signal is frequency modulated stays constant and its frequency varies according to the amplitude variations of the audio signal. When the input signals amplitude increases (ie during the positive half cycle) the frequency of the carrier increases too, on the other hand when the input signal decreases in amplitude (negative half-cycle or no signal) the carrier frequency decreases accordingly.

The output frequency of the transmitter is adjustable from 88 to 108 MHZ, which is the FM band that is used for radio broadcasting. The circuit as we have already mentioned consist of four stages. Three RF stages and one audio preamplifier for the modulation. The first RF stage is an oscillator is